A novel surface muon capture system with a large acceptance was proposed based on the China spallation neutron source(CSNS).This system was designed using a superconducting solenoid where a long graphite target was pu...A novel surface muon capture system with a large acceptance was proposed based on the China spallation neutron source(CSNS).This system was designed using a superconducting solenoid where a long graphite target was put inside it.Firstly,the spin polarization evolution was studied in a constant uniform magnetic field.As the magnetic field can interact with the spin of the surface muon,both the spin polarization and production rate of the surface muons collected by the new capture system were calculated by the G4beamline.Simulation results showed that the surface muons could still keep a high spin polarization([90%)with different magnetic fields(0–10 T),and the larger magnetic field is,the more surface muons can be captured.Finally,the proton phase space,Courant–Snyder parameters,and intensities of surface muons of different beam fractions were given with magnetic fields of 0 and 5T.The solenoid capture system can focus proton and surface muon beams and collect p?and l?particles.It can also provide an intense energetic positron source.展开更多
Considering the mixture after muon-catalyzed fusion(μCF) reaction as overdense plasma,we analyze muon motion in the plasma induced by a linearly polarized two-colour laser,particularly,the effect of laser parameters ...Considering the mixture after muon-catalyzed fusion(μCF) reaction as overdense plasma,we analyze muon motion in the plasma induced by a linearly polarized two-colour laser,particularly,the effect of laser parameters on the muon momentum and trajectory.The results show that muon drift along the propagation of laser and oscillation perpendicular to the propagation remain after the end of the laser pulse.Under appropriate parameters,muon can go from the skin layer into field-free matter in a time period of much less than the pulse duration.The electric-field strength ratio or frequency ratio of the fundamental to the harmonic has more influence on muon oscillation.The laser affects little on other particles in the plasma.Hence,in theory,this work can avoid muon sticking to α effectively and reduce muon-loss probability in μCF.展开更多
This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the si...This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the signal cable to PMT (R3600_06) and characters of the high voltage divider,terminal reflection method is used for measuring the signal attenuation with a practical way to eliminate contribution of the pulse baseline.Comparison measurement data-taking method (with charge-to-digital conversion) was carried out by using open-ended cables,confirming that terminal reflection method is a fast and convenient,and suitable to online calibration of the signal attenuation for Tibet MD-A.At 26℃,the measured attenuation coefficient with the 250-m cable connected permanently to the PMT,was ～13.9%.The cable frequency response was measured by using the sinusoidal signals.The method could be used to study time dispersion of signals produced with Tibet MD-A detector via Fourier analysis.展开更多
20世纪30年代，研究宇宙线的天文学家见证了一个“奇迹”发生的时刻。他们发现了一种新的粒子——μ介子，它像电子一样带一个负电荷，但质量却介于电子和质子之间。这一发现是如此令人吃惊，而这种粒子又是如此的意料之外，使得诺贝尔...20世纪30年代，研究宇宙线的天文学家见证了一个“奇迹”发生的时刻。他们发现了一种新的粒子——μ介子，它像电子一样带一个负电荷，但质量却介于电子和质子之间。这一发现是如此令人吃惊，而这种粒子又是如此的意料之外，使得诺贝尔奖得主伊西多·艾萨克·拉比（Isidor Isaac Rabi）不禁调侃道：“这是谁点的？”展开更多
基金supported by the National Natural Science Foundation of China(No.11527811)
文摘A novel surface muon capture system with a large acceptance was proposed based on the China spallation neutron source(CSNS).This system was designed using a superconducting solenoid where a long graphite target was put inside it.Firstly,the spin polarization evolution was studied in a constant uniform magnetic field.As the magnetic field can interact with the spin of the surface muon,both the spin polarization and production rate of the surface muons collected by the new capture system were calculated by the G4beamline.Simulation results showed that the surface muons could still keep a high spin polarization([90%)with different magnetic fields(0–10 T),and the larger magnetic field is,the more surface muons can be captured.Finally,the proton phase space,Courant–Snyder parameters,and intensities of surface muons of different beam fractions were given with magnetic fields of 0 and 5T.The solenoid capture system can focus proton and surface muon beams and collect p?and l?particles.It can also provide an intense energetic positron source.
基金Supported by Natural Science Foundation of Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.20091025)
文摘Considering the mixture after muon-catalyzed fusion(μCF) reaction as overdense plasma,we analyze muon motion in the plasma induced by a linearly polarized two-colour laser,particularly,the effect of laser parameters on the muon momentum and trajectory.The results show that muon drift along the propagation of laser and oscillation perpendicular to the propagation remain after the end of the laser pulse.Under appropriate parameters,muon can go from the skin layer into field-free matter in a time period of much less than the pulse duration.The electric-field strength ratio or frequency ratio of the fundamental to the harmonic has more influence on muon oscillation.The laser affects little on other particles in the plasma.Hence,in theory,this work can avoid muon sticking to α effectively and reduce muon-loss probability in μCF.
基金supported by the National Natural Science Foundation of China (No.111 072552430)the Key Laboratory of Particle Astrophysics,Institute of High Energy Physics,Chinese Academy of Sciences
文摘This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the signal cable to PMT (R3600_06) and characters of the high voltage divider,terminal reflection method is used for measuring the signal attenuation with a practical way to eliminate contribution of the pulse baseline.Comparison measurement data-taking method (with charge-to-digital conversion) was carried out by using open-ended cables,confirming that terminal reflection method is a fast and convenient,and suitable to online calibration of the signal attenuation for Tibet MD-A.At 26℃,the measured attenuation coefficient with the 250-m cable connected permanently to the PMT,was ～13.9%.The cable frequency response was measured by using the sinusoidal signals.The method could be used to study time dispersion of signals produced with Tibet MD-A detector via Fourier analysis.
文摘20世纪30年代，研究宇宙线的天文学家见证了一个“奇迹”发生的时刻。他们发现了一种新的粒子——μ介子，它像电子一样带一个负电荷，但质量却介于电子和质子之间。这一发现是如此令人吃惊，而这种粒子又是如此的意料之外，使得诺贝尔奖得主伊西多·艾萨克·拉比（Isidor Isaac Rabi）不禁调侃道：“这是谁点的？”
